Okay, where to begin?
Carl - Always hated him from the first two seasons, and even though he may now have some redeeming qualities, I still don't like him much.
Andrea - Pretty great in the comics, stupid bitch on the show, disappointing.
Glen - When from nerdy Pizza boy to badass zombie stomper with hot girlfriend, an inspiration to most of us including me.
Merle - Merle is one of my favourite characters from the show, which is why I don't want him to die, but I won't be surprised if he does get killed.
Michonne - So far had no impact in the tv show, real big letdown from her comic counterpart, reason why in the spoiler tag... (Spoiler is from issue #33
Rick - Rick is the most badass character on the show, and seems to be heading in a very similar direction to the comics, and him going insane makes for some pretty cool scenes (how creepy was the Lori ghost eh?) I get the feeling he is going to do something drastic soon, just unsure of what it is.
Oh and btw in the last episode when he saw Lori, did it seem like he was screaming at everyone, not just the new guys?